Page 310 - Reservoir Formation Damage

290 Reservoir Formation Damage

Radial Filtration Applications

Fisk et al. (1991) conducted radial filtration experiments using a
seawater-based partially hydrolized polyacrylamide mud. Their Figure 4
provides the measured dynamic and static filtrate volumes versus filtration
time data. Judging by their Figure 4, their static filtration data contains
only three distinct measured values. This data is insufficient to extract
meaningful information on the values of the A and C coefficients by
3
regression of Eq. 12-80, because the calculation of In [-q~ dq/dt\ requires
a two step, sequential numerical differentiation—first to obtain the filtrate
flow rate q = dQ/dt by differentiating the filtrate volume Q, and then
differentiating q to obtain dq/dt. On the other hand, their dynamic
filtration data is limited to the filtrate volume. As explained in the
previous section on the determination of parameters, the determination
of all coefficients of A, B, C, and D by means of Eqs. 12-49 and 12-65
requires both the filtration volume and filter cake thickness measurements.
Therefore, the Fisk et al. (1991) radial filtration data has more missing
parameter values, which had to be approximated as given in Table 12-1.
Figure 12-11 shows, the model predicts the measured dynamic and static

10 20 30 40 50 60
Filtration Time, t, min
Figure 12-11. Comparison of the predicted and measured filtrate volumes for
radial filtration of a sea-water based partially hydrolized polyacrylamide drilling
mud (Civan, F., 1998; reprinted by permission of the AlChE, ©1998a AlChE.
All rights reserved).